Mu'adh (May Allah bepleased with him) reported that Messenger of Allah ﷺ sent me (as a governor of Yemen) and instructed me thus:
"You will go to the people of the Book. First call them to testify that 'there is no true god except Allah, that I am (Muhammad ﷺ) the Messenger of Allah.' If they obey you, tell them that Allah has enjoined upon them five Salat (prayers) during the day and night; and if they obey you, inform them that Allah has made Zakat obligatory upon them; that it should be collected from their rich and distributed among their poor; and if they obey you refrain from picking up (as a share of Zakat) the best of their wealth. Beware of the supplication of the oppressed, for there is no barrier between it and Allah".

[Al-Bukhari and Muslim].

وعن معاذ رضي الله عنه قال : بعثني رسول الله ﷺ فقال: "إنك تأتي قومًا من أهل الكتاب، فادعهم إلى شهادة أن لا إله إلا الله، وأني رسول الله ، فإن هم أطاعوا لذلك، فأعلمهم أن الله قد افترض عليهم خمس صلوات في كل يوم وليلة، فإن هم أطاعوا لذلك، فإياك وكرائم أموالهم. واتق دعوة المظلوم فإنه ليس بينها وبين الله حجاب" ((متفق عليه)) .